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45 lines
1.2 KiB
45 lines
1.2 KiB
4 months ago
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package sample;
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import javassist.*;
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/*
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A very simple sample program
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This program overwrites sample/Test.class (the class file of this
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class itself) for adding a method g(). If the method g() is not
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defined in class Test, then this program adds a copy of
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f() to the class Test with name g(). Otherwise, this program does
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not modify sample/Test.class at all.
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To see the modified class definition, execute:
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% javap sample.Test
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after running this program.
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*/
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public class Test {
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public int f(int i) {
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return i + 1;
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}
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public static void main(String[] args) throws Exception {
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ClassPool pool = ClassPool.getDefault();
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CtClass cc = pool.get("sample.Test");
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try {
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cc.getDeclaredMethod("g");
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System.out.println("g() is already defined in sample.Test.");
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}
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catch (NotFoundException e) {
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/* getDeclaredMethod() throws an exception if g()
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* is not defined in sample.Test.
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*/
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CtMethod fMethod = cc.getDeclaredMethod("f");
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CtMethod gMethod = CtNewMethod.copy(fMethod, "g", cc, null);
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cc.addMethod(gMethod);
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cc.writeFile(); // update the class file
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System.out.println("g() was added.");
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}
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}
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}
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